1. Field of the Invention
The present invention relates to a pressurized fluid feed system for temporary connection to a fluid system feeding user device.
2. Description of the Prior Art
As is known, such a fluid system is formed mainly of a fluid generating circuit and a fluid distributor circuit to which the user devices are connected.
In some applications, it is necessary to verify and check the operation of the devices using the fluid distributor circuit from another pressurized fluid feed system, the generating circuit not being able to be brought into service.
For example, in the aeronautic field, aircraft have a fluid system formed of a pressurized fluid generating circuit and a fluid distributor circuit feeding user devices, such, for example, as the flight commands, the landing gear, the braking members, etc . . .
In general, three identical fluid systems are provided in parallel in an obvious concern for safety.
The pressurized fluid generating circuit of one of the three systems includes, briefly, at least one hydraulic pump connected to an engine of the aircraft through which the rotor of the pump is driven in rotation, the pump thus transmits the fluid, coming from a feed pipe, at a given pressure to the distributor circuit comprising the devices.
An outlet pipe for the fluid coming from the user devices is connected, through a filter, to a tank itself connected, by means of a pipe, to the fluid generating circuit.
Thus, when the engines of the aircraft are operating, the user devices are able to be actuated by the pilot.
On the other hand, when the aircraft is being overhauled or assembled in hangars designed for these purposes, it is obvious that the engines cannot operate or be brought into service in these premises for safety reasons.
Consequently, the user devices cannot be controlled and tested by the pressurized fluid generating circuit of the fluid system of the aircraft.
Recourse is had at the present time to two methods for nevertheless being able to control and test the user devices mounted in the aircraft.
The first method consists, schematically, in feeding the distributor circuit of the aircraft directly from a ground feed system. It includes a hydraulic pump connected, upstream, to a hydraulic central unit and, downstream to a console for controlling and regulating the pressurized fluid. This console is connected to the distributor circuit of the aircraft and the return from the user devices passes directly through the filter of the circuit to a reservoir of the ground feed system, to which the pump is connected.
The tank of the aircraft, in this method, is not connected and is isolated from the ground feed system because of the overpressures to which it might be subjected and which might possibly cause it to blow out.
That involves appreciable disadvantages and high costs, since it is necessary to drain the return pipes, to make connections to the internal pipes of the fluid system of the aircraft, thus causing wear and deterioration of the connections.
In addition, during final filling of the fluid system of the aircraft, air risks getting in and causing harmful effects (emulsion, cavitation) in the ducts and pipes of the circuits.
The second method consists, schematically, in connecting each distributor circuit of the aircraft to a depot test bench in this case, each tank of the aircraft is connected to the whole of the circuit while being kept under constant pressure during the time required for testing and checking the user devices.
This method gets over some of the drawbacks of the first method but nevertheless raises difficulties related to the noise, to the congestion particularly of the working zones and to the cost of putting this method into practice. A depot test bench is necessary for each circuit or fluid system of each aircraft.